After months of crashes and lockups whenever I rebooted into windows the problem has been diagnosed and solved! Turns out that my motherboard, an Asus A7V didn't want to play nicely with my video card, an Asus 7700 (NVidia Geforce2). The fact they are from the same manufacturer doesn't seem to make a difference. After my buddy Tiggersol mentioned that the lockups might be caused by this, a quick trip to groups.google.com and then to http://www.geforcefaq.com revealed that the I/O voltage was wrong.
According to the website and the motherboard manual, the voltage default is 3.56V, and it should be dropped to 3.35V for better performance (ie: not having windows (xp, 98, 2k) lock up completely while surfing for no reason). For some reason my motherboard was already jumpered to 3.35V... moving it to 3.56V resulted in it locking up even faster, but moving it up one to 3.65V, and a BIOS update (to 1009) resulted in..... stability! I actually spent the whole day in windows, playing games, surfing..... doing things that I used to do with fear as I knew that any second my box could lock up.
Now if I used Windows more than once a week or month this problem probably would have been solved long ago :)
In other news, the new kitten is still un-named.... she's got a definite personality, but neither I nor my SO have found a name that fits that so far. Fleabag doesn't work anymore, and the only other ones I've thought of were "Chewie" (she's teething, mostly on my fingers) and "Sandy" (short for Sandpaper Tongue of Death, which she uses on my fingers before teething on them). Neither of these seem quite "Right" yet.